I have a 91 Firebird that I recently swapped out the old
drum, 2.73, neg. traction rear end for a rear end out of a 89 Firebird with
disks, 3.08, posi. traction 9 bolt rear

I believe they are 3.08's but could be 3.23 gears.

I am not completely sure if this rear came out of a 89 Firebird as this info was given to me from the guy I bought it from.

I just found out my rear brakes are barley working. I had the rear end up on jacks and when I started the engine and put the transmission into drive while holding down the brakes, the tires kept spinning slowly.

Do I need the correct 4 disk brake proportion valve? if so which one should I buy?

or could this be an e-brake cable adjustment issue?

Thanks!

 

Funny thing is the e-brake seems to work perfectly. When you pull the e brake the mechanism on the caliper travels fully till it hits the stopper, but the rear still doesn't lock and I can spin the tire with my hand.

 

First determine whether you have a 9- or 10-bolt (3.08 and 3.23's are 10-bolt gears).

Second determine whether you have iron Delco-Moraine calipers (82-88) or whether you have alum PBR calipers (89+).

JamesC

 

Both. Either find the correct prop valve or put an adjustable valve in the rear line. You may need e-brake components (lever etc.) from the donor series car. I'll soon be doing the same thing. There's another active thread about the same thing. Plus do some searches.

 

I was hoping you would reply to this lol, Ive been searching around and noticed you know everything about these axles.

It is a 9 bolt borg warner but not sure what gears I have, when I spin the output yoke, the rotors spin about 3 and a quarter turns, could they be 3.23's

But not sure about the calipers though. Ill see if I can find out.

 

I tried some searching but I dont have to much time, and skim through alot durring the day but Ill see if I can find that thread.

The e brake, I believe is workings like its supposed to. When I pull the e brake the mechanisms on the calipers hit the stopper and cannot go any farther, so I'm guessing they just dont have enough pressure so that the e brake works when engaged... maybe?